以方沸石负载Ni(Ⅱ)催化剂修饰的电极电氧化甲醇(英文)

There is a high overvoltage in the oxidation of methanol in fuel cells,and so modified electrodes are used to decrease it.A modified electrode that used Ni(II) loaded analcime zeolite to catalyze the electrooxidation of methanol in alkaline solution was proposed.Analcime zeolite was synthesized by hydrothermal synthesis,and Ni(II) ions were incorporated into the analcime structure,which was then mixed with carbon paste to prepare modified electrode.The electrocatalytic oxidation of methanol on the surface of the modified electrode in alkaline solution was investigated by cyclic voltammetry and chronoamperometry.The effects of the scan rate of the potential,concentration of methanol,and amount of zeolite were investigated.The rate constant for the catalytic reaction of methanol was 6 × 103 cm3 mol-1 s-1 from measurements using chronoamperometry.The proposed electrode significantly improved the electron transfer rate and decreased the overpotential for methanol oxidation.     

A comparison on efficiency of virgin and sulfurized agro-based adsorbents for mercury removal from aqueous systems

Mercury adsorption by sulfur impregnated adsorbents seems to be one of the most efficient ways for removal of this toxic metal ion from wastewater and atmosphere. The aim of this work was to develop a method for preparation of low-cost sulfurized adsorbent from agricultural wastes; this approach combines two stages of (i) chemical activation with phosphoric acid and (ii) impregnation with powdered sulfur, in one step only. The physico-chemical properties of sulfurized adsorbent (AC-S) were determined with BET, FT-IR, Eschka method and pH_PZC measurements, and compared with those of the virgin sample (AC). It was found that sulfurization according to this method can introduce about 8 wt.% sulfur into the structure of adsorbent, in the forms of C–S, S–H, S–S and S=O functional groups. Although during the sulfur introduction processes, a decrease in surface area and micropore volume of the sulfurized adsorbent is to be expected, not only such decrease did not occur in this work, but a large increase in microporosity was seen. Thereupon, both the sulfur functionalities and extended microporosity of AC-S lead to higher capability of this sample for mercury adsorption rather than AC. Finally, the kinetics and equilibrium of mercury adsorption from aqueous solutions were studied for AC and AC-S.     

Cu1.5PMo12O40 as an efficient, mild and heterogeneous catalyst for the condensation of indole with carbonyl compounds

Bis(indoyl)methanes have been synthesized in excellent yields in the presence of catalytic amount of Cu_1.5PMo₁₂O₄₀ in molten tetraethylammonium chloride as an ionic liquid. The catalyst is recovered and recycled.     

Numerical analysis and computational testing of a high accuracy Leray‐deconvolution model of turbulence

We study a computationally attractive algorithm (based on an extrapolated Crank‐Nicolson method) for a recently proposed family of high accuracy turbulence models, the Leray‐deconvolution family. First we prove convergence of the algorithm to the solution of the Navier‐Stokes equations and delineate its (optimal) accuracy. Numerical experiments are presented which confirm the convergence theory. Our 3d experiments also give a careful comparison of various related approaches. They show the combination of the Leray‐deconvolution regularization with the extrapolated Crank‐Nicolson method can be more accurate at higher Reynolds number that the classical extrapolated trapezoidal method of Baker (Report, Harvard University, 1976). We also show the higher order Leray‐deconvolution models (e.g. N = 1,2,3) have greater accuracy than the N = 0 case of the Leray‐α model. Numerical experiments for the 2d step problem are also successfully investigated. Around the critical Reynolds number, the low order models inhibit vortex shedding behind the step. The higher order models, correctly, do not. To estimate the complexity of using Leray‐deconvolution models for turbulent flow simulations we estimate the models' microscale.© 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008     

Design and synthesis of a new series of amphiphilic peptide-β-cyclodextrins as phase transfer carriers for glucosamine

A new series of amphiphilic β-cyclodextrins were designed and synthesized by grafting peptide chains on to all primary hydroxyl groups via ester bond formation. The desired amphiphilic structures have been produced from ester connection between the C-6 of β-cyclodextrin and the carboxyl group of N-acetylated resides: H₂N-Leu-COOH, H₂N-Leu-Gly-COOH, H₂N-Leu-Gly-Leu-COOH, and H₂N-Leu-Gly-Leu-Gly-COOH (3a-d). The synthetic pathway involves selective bromination of all primary hydroxyls of β-cyclodextrins and then substitution with the carboxylate moiety of the mentioned N-acetyl residues in the presence of DBU (1,8-diazabicyclo[5,4,0]undec-7-ene). The ability of the synthetic compounds for extraction and phase transfer of glucosamine, as a hydrophilic organic compound, was then studied. The results showed a considerable ability of these amphiphilic compounds for extraction and a selective tendency of 3c for phase transfer of glucosamine.     

Encapsulation of 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione into the silica gel matrix for capturing uranium(VI) ion species

Journal of Radioanalytical and Nuclear Chemistry - The thenoyl-trifluoro-acetone (tta: 4,4,4-Trifluoro-1-(2-Thienyl)-1,3-butanedione) has been successfully encapsulated into the silica gel matrix...     

The effect of the chemical composition and the volume of coated carbonate calcium on epoxy paint properties

Russian Journal of Applied Chemistry - Titanium dioxide (TiO2) is widely used in the paint industry as a white pigment. To reduce the high cost of TiO2, mineral fillers such as different calcites...     

Microwave‐Assisted Catalyst Free Three Component Synthesis of Mono and Bis Spiro Pyrazolopyridines in Solvent Free Reaction

Multicomponent synthesis of mono and bis‐spiro pyrazolopyridines from isatin derivatives, indanedione, and 3‐methyl‐5‐aminopyrazole under microwave irradiation in the absence of any catalyst or solvent with high yield and short reaction time is reported.     

Synthesis of new dyes containing double tetrazole groups for sensitization of TiO<Subscript>2</Subscript> nanoparticles in dye-sensitized solar cells

Di(1H-tetrazol-5-yl)methane is employed as a new electron acceptor group in the synthesis of two metal-free organic dyes containing triphenylamine donor group. Dye-sensitized nanocrystalline TiO₂ solar cell (DSSC) applying these novel dyes is constructed for consideration of their photovoltaic properties. The electronic properties of the dyes are also considered with the aid of theoretical calculations. The DSSC constructed from 4-(2,2-di(1H-tetrazol-5-yl)vinyl)-N,N-diphenylaniline (T1) shows a short-circuit photocurrent density of 13.38 mA cm^?2, an open circuit voltage of 578 mV, and a fill factor of 0.54, with a resulted solar energy-to-electricity conversion efficiency of 4.18% under simulated 1 sun irradiation (100 mW cm^?2). This result reveals that the dye with the di(1H-tetrazol-5-yl)methane anchoring group injects more electrons to the conduction band of TiO₂ in comparison with its analogs with single tetrazole ring in their anchoring group. It is found that in spite of a red-shift of the absorption spectrum resulted from the lengthening of the molecule, the dye with two di(1H-tetrazol-5-yl)methane groups gives lower performance than the dye with a single electron acceptor.